Solid-state memory, such as flash, is currently in use in solid-state drives (SSDs) to augment or replace conventional hard disk drives (HDDs), writable CDs (compact disk) or writable DVD (digital versatile disk) drives, collectively known as spinning media, and tape drives, for storage of large amounts of data. Flash and other solid-state memories have characteristics that differ from spinning media. Yet, many solid-state drives are designed to conform to hard disk drive standards for compatibility reasons, which makes it difficult to provide enhanced features or take advantage of unique aspects of flash and other solid-state memory. Storage systems, whether applying solid-state memory such as flash, or hard disk drives, or hybrid combinations of the two, are vulnerable to disasters such as multiple component failures, system power loss, data theft and physical theft (i.e., loss of both components and data). In addition, conventional storage architectures may allow for exposure of the data in the case of physical theft of a storage module.
Traditionally, replicated storage systems are used to enable disaster recovery if a single system fails. Many of these systems are configured as a “mirrored pair” of systems, where writes go to one system and copied or mirrored data is written to the other system. Mirrored pair systems typically need to be in a secure environment. Data written to one system is mirrored to another system, so both systems need to be protected. This is often solved by encrypting data before the data reaches a second system. However, the encrypting makes it difficult, impractical or impossible to compress data on the second system. Consequently, an increased amount of storage is needed to store user data and an increased amount of bandwidth is needed to transfer writes to the second system. In addition, it may be possible for an operator of one of the systems to steal data by disconnecting one system from the other system(s) and reading the data independently.
It is within this context that the embodiments arise.